Entry of Nanoparticles into cells: Characterization of Nanoparticles as tools to study endocytic pathways and intracellular transport

Research on nanoparticles have evolved into biological applications with large expectations for the use of magnetic iron oxide nanoparticles and fluorescent Quantum dots in different imaging techniques both for tumor targeting and drug delivery in humans and as probes at the cellular level. In this research project we will adress several questions concerning the fate of these nanoparticles after binding to the cells that need to be answered in connection with their use in cell biological studies and certa inly before applying them in humans: To which extent are they internalized? Can they be recycled out again, or are they degraded by the cell? If they accumulate in the cells, to which extent do they disturb trafficking of natural ligands, and do they have a cytotoxic effect? An important issue is whether the answer to the questions above is dependent on the type and size of the nanoparticles. Furthermore, use of the nanoparticles will provide us with important new tools for characterizing different types of endocytic and intracellular sorting pathways: 1) Apply Quantum dots conjugated to different cell surface binding proteins in confocal microscopy imaging. 2) We will develop methods for purifying endocytic vesicles based on, a) magnetic separation of ve sicles containing endocytosed paramagnetic nanoparticles, or b) a FACS-based subcellular isolation of Quantum dot-labelled endocytic vesicles. Knowledge about how the nanoparticles are affecting cellular processes and endocytic pathways will be important for the development of functional applications based on nanoparticles such as targeted drug delivery systems and diagnostic in vivo imaging systems.